JPS61250825A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium of a thin ferromagnetic metallic film type having a small coefft. of friction and improved wear resistance and durability by forming a liquid lubricating agent layer suspended with pulverous solid particles on the thin ferromagnetic metallic film. CONSTITUTION:The pulverous solid particles may be either pulverous inorg. particles or pulverous org. particles and the particles having the grain size ranging 0.01-0.3mum are used. A fatty acid, fatty acid ester, fatty acid amide, aliphat. alcohol, paraffin, fluorine surface active agent, etc. are used for the liquid lubricating agent. The liquid lubricating agent layer suspended with palverous solid particles is formed by a method for coating the liquid lubricating agent which is diluted into a suitable solvent and is dispersed therein with the above-mentioned pulverous solid particles on, for example, the surface of the thin ferromagnetic metallic film. The pulverous solid particles move freely in the liquid lubricating agent layer without being fixed in the liquid lubricating agent layer 4 which are formed on the film 2 surface and in which the particles 3 are suspended. The cutting away of the pulverous solid particles by the contact with a magnetic head is thus obviated and the always good lubricating effect is obtd. by the self-restoration.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a so-called ferromagnetic metal film formed by forming a ferromagnetic metal thin film as a magnetic layer on a non-magnetic support by vapor deposition, ion blasting, sputtering, etc. The present invention relates to a thin-film magnetic recording medium.

[Summary of the invention]

The present invention provides a magnetic recording medium in which a ferromagnetic metal thin film is formed as a magnetic layer on a non-magnetic support, in which a liquid lubricant layer in which solid fine particles are suspended is formed as a protective film on the surface of the ferromagnetic metal thin film, thereby improving durability. In addition to improving the performance, the aim is to prevent deterioration of the regenerated output due to wear particles.

[Conventional technology].

Conventionally, as a magnetic recording medium, r-
Fe20y, Fei04. γ containing Co
FeZoff, rFe*Oa containing Co
, r-Fe20. Bertolide compound of and Fe5Oa.

Powder magnetic materials such as ferromagnetic powders of oxides such as CO-containing bertolide compounds, CrO2, or alloy magnetic powders containing Fe, Co, Ni, etc. as main components are combined with vinyl chloride-vinyl acetate copolymers, polyester resins, etc. Coated magnetic recording media, which are obtained by coating and drying a magnetic paint dispersed in an organic binder such as a polyurethane resin, are widely used.

On the other hand, with the increasing demand for high-density magnetic recording, ferromagnetic metal materials such as metals such as iron, cobalt, nickel, and alloys such as Co-Ni have been developed using vacuum evaporation, spackling, and ion brating methods. A so-called ferromagnetic metal thin film type magnetic recording medium, which is directly deposited on a non-magnetic support such as a polyester film or a polyimide film, using a vacuum thin film forming technique such as the above, has been proposed and is attracting attention. This ferromagnetic metal thin film magnetic recording medium not only has high coercive force He and residual magnetic flux density Br, but also allows the thickness of the magnetic layer to be made extremely thin, resulting in significant thickness loss during recording demagnetization and reproduction. It has many advantages in terms of magnetic properties, such as being small and being able to increase the packing density of the magnetic material because there is no need to mix an organic binder, which is a non-magnetic material, into the magnetic layer.

[Problem that the invention seeks to solve]

However, in the above-mentioned ferromagnetic metal thin film type magnetic recording medium, the surface smoothness of the magnetic layer is extremely good, so the substantial contact area becomes large, and adhesion phenomena (so-called sticking) tend to occur. It has many drawbacks in terms of durability, running performance, etc., such as a large coefficient of friction, and improving these issues is a major issue.

For example, attempts have been made to improve the durability and runnability by coating the surface of the magnetic layer of the magnetic recording medium, that is, the ferromagnetic metal thin film, with a lubricant or the like to form a protective film. In this case, the coefficient of friction is initially reduced and running properties are improved, but since the adhesion of the lubricant to the ferromagnetic metal thin film is weak, this lubricant is gradually scraped away by a magnetic head, etc. The disadvantage is that the effect decreases rapidly.

Alternatively, as described in JP-A No. 56-101650, a thin resin film is provided on the surface of a ferromagnetic metal thin film, and minute protrusions with solid particles as cores are formed in this thin resin film to improve slipperiness and resistance. Attempts have been made to improve wear resistance, etc.
In this case as well, the microprotrusions are gradually scraped off, making it difficult to maintain the effect over a long period of time.

The present invention was proposed in view of the above circumstances, and an object of the present invention is to provide a ferromagnetic metal thin film type magnetic recording medium that has a small coefficient of friction and improved wear resistance and durability. , which attempts to solve the above-mentioned problems.

[Means for solving problems]

As a result of intensive research to achieve the above object, the present inventor has found that a thin film layer of liquid lubricant in which solid particles are suspended so that they can move freely has extremely good lubricity.
It has been found that this material is highly effective in improving wear resistance and durability.

The present invention was completed based on such research results, and is a magnetic recording medium in which a ferromagnetic metal thin film is formed on a non-magnetic support, in which solid fine particles are formed on the ferromagnetic metal thin film. It is characterized by the formation of a floating liquid lubricant layer.

The solid fine particles used in the present invention may be either inorganic fine particles or organic fine particles,
It is preferable to use a particle size within the range of 0.01 to 0.3 μm.

The above-mentioned inorganic fine particles include 5b206. A j! ,o
,.

Z r Og+T i 0213 n Oz+Cr20
3. S i NtlM.

Metal oxides and metal nitrides such as C, MnO, CaF, fluorinated graphite, ferricolloid, and graphite.

Metal carbides, metal halide, etc. can be used.

Further, as the organic fine particles, fluororesin powder such as polytetrafluoroethylene (so-called Teflon),
Acrylic resin beads, melamine resin beads, organic dyes, organic pigments, etc. can be used.

The above organic dyes include amaranth, erythrosine, newcoccin, phloxine B, rose bengal, acid red, tartrazine, sunset yellow FCF, fast green FCF, brilliant blue FCF, indigo carmine, lysole rubin B, rhodamine B, rhodamine B acetate. Rhodamine B stearate, tetrachlorotetrabromofluorescein, tetrabromofluorescein, Sudan ■, Herringdon Pink CN, Fast Acid Magenta, Eosin YS.

Eosin YSK, Phloxine BK, Rose Bengal 5, dibromofluorescein, orange ■, Jodhyalurecein, erythrosin yellow NA, fluorescein, uranine, uranine, quinoline yellow WS, quinoline yellow SS, alizarin cyanine green F, quinizarin green SS, Hiranin conch, light green SF yellow, indigo.

Patent Blue NA, Patent Blue CA, Calpanthrene Blue, Alphazurin FG, Resorcin Brown, Alizurin Purple SS, Violamine R1 Medicated Scaresotoponso-3R, Bonso R, Bonso SX,
Oil Red XO, Fast Trend S, Orange ■, Orange SS, Polar Yellow 5G, Naphthol Yellow S,
Elor AB.

Yellow OB, Metanyl Yellow, Fast Light Yellow 3G, Naphthol Green B, Guinea Green B, Sudan Blue B, and Ori Zulor Purple.

Examples include naphthol blue blank.

The organic pigment mentioned above is Lysol Rubin BCA.

Rake Red C, Rake Red CBA, Resole Red, Resole Red CA, Resole Red BA,
Lysol Red SR, Brilliant Lake Red R, Deep Maroon, Toluidine Red.

Permanent Red, Permanent Orange, Bendesine Orange, Pendesine Yellow G, Brilliant Core Scarle Soto Permanent Red.

Examples include Hansa Orange, Hansa Yellow, and Phthalocyanine Blue.

Furthermore, in order to stabilize running, fine particles of a solid lubricant such as molybdenum disulfide may be added at the same time.

On the other hand, the liquid lubricant used in the present invention includes:
Fatty acids, fatty acid esters, fatty acid amides.

Examples include aliphatic alcohols, paraffins, and fluorosurfactants.

Fatty acids include lauric acid and myristic acid.

palmitic acid, stearic acid, behenic acid, oleic acid,
Those having 12 or more carbon atoms such as linoleic acid and linoleic acid can be used.

Ethyl stearate is a fatty acid ester.

Butyl stearate, amyl stearate, stearic acid monoglyceride, oleic acid monoglyceride, etc. can be used.

Examples of fatty acid amides include caproic acid amide, capric acid amide, lauric acid amide, palmitic acid amide, stearic acid amide, and behenic acid amide.

Oleic acid amide, linoleic acid amide, methylene
・Bisstearamide, ethylene bisstearamide, etc. can be used.

Cetyl alcohol is an aliphatic alcohol.

Stearyl alcohol etc. can be used.

As the paraffin, saturated hydrocarbons such as n-nonadecane, n-tridecane, and n-tocosan can be used.

As the fluorine-based surfactant, perfluoroalkylcarboxylic acid and perfluoroalkylsulfonic acid and Na,
Mg, Zn, A1. Fe, Co.

Salts with Ni etc., perfluoroalkyl phosphate esters, barfluoroalkyl betaines, perfluoroalkyltrimethylammonium salts, perfluoroethylene oxide,
Perfluoroalkyl aliphatic esters and the like can be used.

Alternatively, the general formula %formula%) Phosphate esters and general formulas represented by (RIO) (R20) (R30)P It is also possible to use phosphorous acid esters shown in the following.

In addition, in each of the above formulas, R+, R2, R, and 3 each represent any one of hydrogen, an alkyl group, an allyl group, a phenyl group, and an alkylphenyl group.

Therefore, a liquid lubricant layer in which solid fine particles are suspended can be formed by diluting the liquid lubricant described above in an appropriate solvent, dispersing the solid fine particles, and applying the mixture to the surface of a ferromagnetic metal thin film, for example. Ru.

Here, the coating amount of the liquid lubricant layer is 0.5 to 10
It is preferably 0 mg/a, 1 to 20 mg/rr+
It is more preferable that If the coating amount is too small, the effect of lowering the coefficient of friction and improving wear resistance and durability will not be achieved. On the other hand, if it is too large, a sticking phenomenon will occur between the sliding member and the ferromagnetic metal thin film. On the contrary, the running performance deteriorates.

The packing density of the solid particles dispersed and suspended in the liquid lubricant layer is preferably within the range of 100,000 to 10 million particles/mm, and within this range, the magnetic head will not be clogged. and does not increase dropouts.

In addition, as a solvent for diluting the above liquid lubricant,
The lubricant may be selected as appropriate depending on the type of lubricant, but in general, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, methanol,
Alcohols such as ethanol, propatool, buknol, esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, acetic acid glycol monoethyl ether,
Ethers such as ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, tetrahydrofuran, and dioxane, aromatic hydrocarbons such as benzene, toluene, and xylene, and hexane.

Aliphatic hydrocarbons such as heptane, methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin 3 Chlorinated hydrocarbons such as dichlorobenzene, trichlorofluoromethane, dichlorodifluoromethane, chlorotrifluoromethane, chlorodifluoromethane , 1.1.2-1-Rechlor 1.2.2-
Fluorohydrocarbons such as trifluoroethylene and 3-dichlorotetrafluoroethylene, water, and mixed solvents thereof are used.

By the way, the magnetic recording medium to which the present invention is applied is one in which a ferromagnetic metal thin film is provided as a magnetic layer on a non-magnetic support, and the material of the non-magnetic support is polyester such as polyethylene terephthalate. Polyolefin products such as polyethylene, polypropylene, cellulose triacetate.

Cellulose derivatives such as cellulose diacetate and cellulose acetate butyrate, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, plastics such as polycarbonate, polyimide, and polyamideimide, light metals such as aluminum alloys and titanium alloys, ceramics such as alumina glass, etc. can be mentioned. The nonmagnetic support may be in any form such as a film, sheet, disk, card, or drum. The surface condition of this nonmagnetic support may or may not be uneven, but it is more preferable to have about 100 to 800 microscopic protrusions.

Further, the ferromagnetic metal thin film that is the magnetic layer is formed as a continuous film by a vacuum thin film forming technique such as a vacuum evaporation method, an ion blating method, or a sputtering method.

In the vacuum evaporation method described above, a ferromagnetic metal material is evaporated by resistance heating, high frequency heating, electron beam heating, etc. under a vacuum of 10-4 to 10-8 Torr, and the evaporated metal (
Generally, in order to obtain a high coercive force, an oblique evaporation method is employed in which the ferromagnetic metal material is deposited obliquely to the substrate. or,
It also includes those in which the above-mentioned vapor deposition is performed in an oxygen atmosphere in order to obtain higher coercive force.

The above-mentioned ion blating method is also a type of vacuum deposition method, in which DC glow discharge and RF glow discharge are caused in an inert gas atmosphere of 10-4 to 10-' Torr, and the ferromagnetic metal material mentioned above on the disk is evaporated during discharge. It is to let them do so.

The above sputtering method involves causing glow discharge in an atmosphere mainly composed of argon gas at 104 to 10 Torr, and using the generated argon gas ions to knock out atoms on the target surface. 2-pole, 3-pole sputtering method, high frequency sputtering method,
Alternatively, there is a magnetron sputtering method using magnetron discharge.

In the case of this sputtering method, Cr or W is used.

A base film such as (2) may be formed in advance.

In any of the above methods, Bi, Sb, Pb, Sn, Ga, and In are preliminarily deposited on the substrate.

By pre-depositing a base metal layer such as Cd, Ge, St, Tβ, etc., and depositing the film in a direction perpendicular to the substrate surface, excellent in-plane magnetic properties can be achieved without magnetic anisotropy orientation. It is suitable for forming a layer, for example, into a magnetic disk.

When forming a metal magnetic thin film using such vacuum thin film forming technology, the ferromagnetic metal materials used include Fe,
In addition to metals such as Co and Ni, C.

-Ni alloy, Co-Pt alloy, Co-Ni-Pt alloy,
Fe-Co alloy, Fe-Ni alloy, Fe-Co-Ni alloy, Fe-Co-B alloy, Co-N1-Fe-B alloy,
Co-Cr alloy or Cr, Aj! Examples include those containing metals such as. In particular, when a Co--Cr alloy is used, a perpendicularly magnetized film is formed.

The thickness of the magnetic layer formed by such a method is 0.
It is about 0.04 to 1 μm.

[Effect]

In the liquid lubricant layer in which the solid particles are suspended, which is formed on the surface of the ferromagnetic metal thin film, the solid particles are not fixed and can freely move in the liquid lubricant layer.
These solid particles are not scraped off by contact with the magnetic head, and self-recovery always provides a good lubrication effect.

〔Example〕

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

Example 1 As shown in FIG.
A ferromagnetic metal thin film (2) was formed by forming a magnetic alloy made of 10N Izo to a thickness of 1500 to 1600 mm by oblique evaporation.

On the other hand, using oleic acid as a liquid lubricant, 10mg/
Oleic acid was diluted with Freon (trade name) so that the amount of oleic acid was 10% by weight, and chromium oxide Cr2O3 corresponding to 10% of the amount of oleic acid was dispersed in the solution. For dispersion, use an ultrasonic homogenizer RVS-300 manufactured by Nippon Seiki Co., Ltd.
It was used. Since undispersed coarse particles may remain, the mixture was passed through a 0.8 μm filter.

The ferromagnetic metal thin film (2) is immersed in an oleic acid solution in which chromium oxide is dispersed in this way, and dried to form a liquid lubricant layer (2) in which solid fine particles (Crzch) (3) are suspended.
4) to obtain a sample tape.

The still time of the obtained sample tape was measured and showed a good result of 120 minutes or more. Note that this still time evaluation device is Sony's CC
I)-V8 was used.

Example 2 A sample tape was obtained in the same manner as in Example 1, using copper phthalocyanine green as the solid fine particles.

When the still time of the sample tape obtained was measured, it also showed a good result of 120 minutes or more.

Example 3 A sample tape was obtained in the same manner as in Example 1, using perfluoroalkyl phosphate as the liquid lubricant and molybdenum carbide M o C as the solid particles.

The still time of the obtained sample tape was measured and similarly showed a good result of 120 minutes or more.

Example 4 A sample tape was obtained in the same manner as in Example 1, using perfluoroalkyl phosphate as the liquid lubricant and calcium fluoride CaF2 as the solid particles.

The still time of the obtained sample tape was measured and similarly showed a good result of 120 minutes or more.

Example 5 A sample tape was obtained in the same manner as in Example 1, using stearamide as the liquid lubricant and rose bengal as the solid particles.

The still time of the obtained sample tape was measured and similarly showed a good result of 120 minutes or more.

Example 6 A sample tape was obtained in the same manner as in Example 1, using stearamide as the liquid lubricant and polytetrafluoroethylene (trade name: Teflon) powder as the solid particles.

The still time of the obtained sample tape was measured and similarly showed a good result of 120 minutes or more.

Comparative Example 66 pJ i z of CO was deposited on a base film made of polyethylene terephthalate with a thickness of 12 μm. A magnetic alloy consisting of the following was formed to a thickness of 1,500 to 1,600 mm by oblique vapor deposition to form a ferromagnetic metal thin film.

Next, the ferromagnetic metal thin film was immersed in an oleic acid solution diluted with Freon (trade name) to form a liquid lubricant layer to obtain a sample tape.

When the still time of the obtained sample tape was measured, it was found to be extremely short, approximately 9 minutes, and was inferior in durability.

〔Effect of the invention〕

As is clear from the above explanation, in the present invention, a liquid lubricant layer with suspended solid particles is used as a protective film for a ferromagnetic metal thin film type magnetic recording medium, so it has excellent self-restoring properties and is suitable for magnetic heads. Good lubricity without being scraped off by contact with.

A protective film exhibiting wear resistance is formed. Therefore, the frictional characteristics and durability of the resulting magnetic recording medium can be significantly improved, and deterioration of reproduction output can be prevented.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a main part showing the structure of an embodiment of a magnetic recording medium to which the present invention is applied. 1...Base film (non-magnetic support) 2...Ferromagnetic metal thin film 3...Solid fine particles 4...Liquid lubricant layer

Claims (1)

[Claims] A magnetic recording medium comprising a ferromagnetic metal thin film formed on a non-magnetic support, characterized in that a liquid lubricant layer in which solid particles are suspended is formed on the ferromagnetic metal thin film. magnetic recording medium.